The present invention relates generally to imaging objects and more particularly to a method and apparatus for improving the signal to noise ratio of an image formed of an object hidden in or behind a semi-opaque random media, the object being either opaque, transparent or semi-transparent.
Many objects that we wish to observe are hidden inside or behind some kind of semi-opaque random media. Some examples are tumors inside a breast, defects in a semiconductor, objects in the ocean or in a cloud or in smoke. The above are applications in medicine, electronics, military, and commercial fields.
When a light pulse propagates through a random medium, some of the light is multiply scattered. The multiple scattering of light reduces the intensity of the signal and increases the noise on the signal arising from the randomly scattered light. The reduction in signal and increase in noise from multiple scattered light are the main reasons why one cannot see through an optically thick random medium. Thus, one has to reduce the scattered light noise in order to enhance the quality of the image.
The following references are pertinent to the invention: An article entitled Simulation of Laser Tomoscopy In A Heterogeneous Biological Medium, J. M. Maarek etc., Med & Bio. Eng. & Computer, Jul. 1986, pp. 407-414; U.S. Pat. No. 4,099,060; U.S. Pat. No. 4,203,037; U.S. Pat. No. 4,066,901; U.S. Pat. No. 4,207,892; U.S. Pat. No. 4,515,165; U.S. Pat. No. 4,570,638; and U.S. Pat. No. 4,212,306.
It is an object of this invention to provide a new and improved technique for improving the signal to noise ratio of an image formed of an object hidden in or behind a semi-opaque random media.